None
Not applicable.
The present invention generally relates to abrasive grinding tools and more particularly to grinding tools having a precisely controlled array or pattern of abrasive particles thereon.
Heretofore, abrasive particles were applied to the exterior surfaces of or embedded in grinding elements by a variety of techniques. Regardless of the technique, a random distribution of abrasive particles characterized the cutting edge of the grinding tool. This can be seen by reference to FIG. 1, which is a photomicrograph at 100 xc3x97 magnification of 40/50 mesh abrasive particles nickel-plated onto a steel core grinding wheel. FIG. 2 is the same wheel at 50 xc3x97magnification it will be seen that the abrasive was nickel plated in a random distribution and at an abrasive concentration that could not be controlled at any given area of the abrasive tool. This means that there is a risk is wheel loading. Moreover, there is little opportunity to adjust abrasive size, type, and geometry of the abrasive particles at any given area of the tool. While the total amount of abrasive particles plated onto the tool can be controlled such control allows for wide latitude in process repeatability and quality control.
Heretofore, the art has achieved specific abrasive patterns on tool surfaces using adhesive foils and printing technology to create non-conductive areas to prevent deposition of Ni during the galvanic plating process. These processes are limited to planar surfaces and do not meet the industry demands to full utilize the performance of superabrasive crystals on the edges or other complex surface geometries of common grinding wheels and other tools. For example, EP 0870578 A1 proposes to hold the abrasive grains in place with an adhesive layer and then drills grooves into the abrasive crystals that protrude from the Ni layer.
Clearly, there exits a need in the art to be able to precisely control the location, concentration, grade, etc. of abrasive crystals applied to tools work surfaces. It is to such need that the present invention is directed.
A method for fabricating an abrasive tool having a work surface commences by applying an electrically non-conductive layer on the work surface of the abrasive tool. A pattern is etched either in the work surface or the non-conductive layer preferably using a laser beam. Metal and abrasive particles are electroplated or electroless plated onto the work surface pattern. The non-conductive layer is removed from the work surface. By multiple repetitions of this method, different sizes and types of abrasive particles in different concentrations may be applied to different areas of the work surface.
Alternatively, an adhesive can be applied as a layer on the work surface of the abrasive tool. A negative pattern then is etched in the adhesive layer, i.e., the adhesive where no abrasive is desired is etched away. Abrasive partides then can contact the work surface to be adhered thereon to the remaining adhesive. Again, by multiple repetitions of this method, different sizes and types of abrasive particles in different concentrations may be applied to different areas of the work surface. Metal again can be electroplated or electrolessly plated onto the work surface.
Consonant in these two embodiments is the use of a laser or other precise removal system to determine the precise location where abrasive particles are to be adhered onto the work surface of an abrasive tool. Moreover, both embodiments are amendable to multiple repetitions and to yielding metal coated work surfaces with precisely located abrasive particles of controlled size, type, and concentration by location.